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A Wacker-Type Strategy for the Synthesis of Unsymmetrical POCsp3E-Nickel Pincer Complexes
Organometallics ( IF 2.5 ) Pub Date : 2020-11-09 , DOI: 10.1021/acs.organomet.0c00590
Loïc P. Mangin 1 , Guillaume Michaud 1 , Davit Zargarian 1
Affiliation  

ECE-type pincer complexes have evolved into a diverse family of compounds possessing interesting structural/bonding features, reactivities, and practical applications. An important factor promoting the growth of pincer chemistry is the availability of versatile synthetic pathways that give access to ever-diverse pincer complexes. This report describes the synthesis of pincer–Ni complexes possessing the following features: a central Ni–Csp3 linkage, two different peripheral donor moieties, and two differently sized metallacycles. The synthetic methodology reported herein is based on the reactivity of a phosphinite derived from 2-vinylphenol. Stirring the substrate 2-CH2═CH—C6H4-OP(i-Pr)2, 1, with the NiII precursor {(i-PrCN)NiBr2}n and Et3N at room temperature gave the 6,5-POCsp3PO-type pincer complex {κO,κC,κP-2-[(i-Pr)2P(O)CH2CH]-C6H4-OP(i-Pr)2}NiBr, 2. Conducting this reaction in the presence of an excess of 1 hinders the formation of 2, giving instead the nickellacyclopropane complex {κC,κ,κP-2-[(2-CH2═CH—C6H4O)P(i-Pr)2CHCH]-C6H4-OP(i-Pr)2}NiBr, 3, whereas introducing a second, stronger nucleophile into the reaction mixture leads to the formation of pincer complexes featuring rare 4-membered metallacycles. For instance, using HNR(R′) as nucleophile gave the 6,4-POCsp3N-type pincer complexes {κN,κC,κP-2-[R(R′)NCH2CH]-C6H4-OP(i-Pr)2}NiBr (NR(R′) = N-morpholyl, 4; NPh(Et), 5; NH(i-Pr), 6; NH(Ph), 7; NH(Cy), 8; NH(t-Bu), 9), whereas using HPR2 as nucleophile led to the 6,4-POCsp3P-type pincer complexes {κP,κC,κP-2-[R2PCH2CH]-C6H4-OP(i-Pr)2}NiBr (R = i-Pr, 10; iPh, 11). Single crystal diffraction studies have established the solid-state structures of complexes 211. All the pincer complexes reported here feature 6-membered metallacycles defined by the phosphinite moiety, while the phosphine-oxide moiety in 2 defines a 5-membered metallacycle and 4-membered metallacycles form by the coordination of the amine moieties in 49 and the phosphines in 10 and 11. Cyclic voltammetry measurements on complexes 2, 46, 10, and 11 have shown that these pincer–Ni complexes undergo facile one-electron oxidation.

中文翻译:

Wacker型策略用于合成不对称POC sp 3 E镍钳形配合物

ECE型钳夹复合物已发展成为具有有趣的结构/键合特征,反应性和实际应用的多种化合物。促进钳夹化学生长的一个重要因素是通用合成途径的可用性,这些途径可提供种类繁多的钳夹复合物。该报告描述了具有以下特征的钳子-镍配合物的合成:中心Ni-C sp 3键,两个不同的外围供体部分和两个不同大小的金属环。本文报道的合成方法基于衍生自2-乙烯基苯酚的次膦酸酯的反应性。搅拌该基板2-CH 2 = CH-C 6 H ^ 4 -OP(-Pr)21,与镍II前体{(-PrCN)NIBR 2 } Ñ和Et 3 Ñ在室温下,得到6,5-POC SP 3 PO型钳形络合物{κ øκ Çκ P - 2-[((i- Pr)2 P(O)CH 2 C H] -C 6 H 4 -O Pi- Pr)2 } NiBr,2。在过量1的存在下进行此反应阻碍形成2,给代替nickellacyclopropane复杂{κ Çκκ P -2 - [(2-CH 2 = CH-C 6 H ^ 4 O)P(-Pr)2 ç ħ Ç H] - C 6 H 4 -O Pi -Pr)2 } NiBr,3,而向反应混合物中引入第二个更强的亲核试剂会导致形成具有稀有4元金属环的钳形配合物。例如,使用HNR(R')作为亲核试剂可得到6,4-POC sp 3N型钳形络合物{κ Ñκ Çκ P -2- [R(R')ñ CH 2 C ^ H] -C 6 H ^ 4 -O P-Pr)2 } NIBR(NR(R' )= N-吗啉基,4 ; NPh(Et),5 ; NH(i- Pr),6 ; NH(Ph),7 ; NH(Cy),8 ; NH(t- Bu),9),而使用HPR 2作为亲核试剂可导致6,4-POC sp 3 P型钳夹复合物{κP κ Ç κ P ' -2- [R 2 P CH 2 C ^ H] -C 6 H ^ 4 -O P(I-PR) 2 } NIBR(R =-Pr, 10 ;的pH值, 11) 。单晶衍射研究确定复合物的固态结构, 2 - 11。此处报道的所有钳形复合物均具有由亚膦酸酯部分定义的6元金属环,而膦氧化物部分为2通过49中的胺部分和1011中的膦的配位定义了5元金属环和4元金属环的形式。上的复合物的循环伏安法的测量24 - 610,和11显示,这些钳镍络合物经历容易的单电子氧化。
更新日期:2020-11-23
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